274 



FORESTRY INVESTIGATIONS U. s. DEPARTMENT OF AGKICULTUKE. 



It follows that the forest planter, who desires to produce long and clean shafts and best working 

 quality of timber, must secure and maintain side shade by a close stand, while the landscape 

 gardener, who desires characteristic form, must maintain an open stand and full enjoyment of 

 light for his trees. 



Now, as we have seen, different species afford different amounts of shade, and in proportion 



to the shade which they jvtlbrd can they endure shade. 

 The beech or sugar maple or spruce, which maintain 

 a large amount of foliage under the dense shade of 

 their own crown, show that their leaves can live and 

 functionate with a small amount of light. They arc 

 shade-enduring trees. On the other hand, the black 

 walnut, the locust, the 

 catalpa, the poplars, 

 and the larch show by 

 the manner in which 

 their crowns thin out, 

 the foliage being con- 

 fined to the ends of the 

 branches, that their 

 leaves require more 

 light they are light- 

 needing trees; so that 

 the scale which ar- 

 ranges the trees ac- 

 cording to the amount 

 of shade they exert 

 serves also to measure 

 their slia.de endurance. 

 In making, tlierer 

 fore, mixed planta- 

 tions the different 

 kinds must be. so 

 grouped and managed 

 that the shady trees 

 will not outgrow and 

 overtop the light need- 

 ing. The latter must either have the start of the former or must be 

 quicker growers. 



BATE OF GROWTH. 



Not only do different species grow more or less rapidly in height 

 and girth, but there is in each species a difference in the rate of 

 growth during different periods of life and a difference in the per 

 sistenee of growth. 



It stands to reason that trees grow differently in different soils 

 and situations, and hence we can not compare different species with 

 respect to their rate of growth except as they grow under the same 

 conditions. 



Thus the black walnut may grow as fast as or faster than the ash 

 on a rich, deep, moist, warm soil, but will soon fall to the rear in a 

 wetter, colder, and shallower soil. 



Given the same conditions, some species will start on a rapid upward growth at once, like the 

 poplars, aspen, locust, and silver maple, making rapid progress (the most rapid from their tenth 

 to their fifteenth year), but decreasing soon in rate and reaching their maximum height early. 

 Others, like the spruce, beech, and sugar maple, will begin slowly, often occupying several, 



FIG. 35. Sections of logs showing the relative development of 

 knots. E, from tiro jjrown in the OJK-II : ', from tree yrown 

 in a dense forest; a and c, whorls of knots; b, dead limb: 

 sk, "sound knot;" dk, "dead knot." 



Km. 30. Srheme to illustrate the ar- 

 fan^t'Mit'iitof annual growth. 1, '_', I!, 

 nt the jiarts of 1 IK- stnn 

 g the fii'st, siTiHiil. I hied, 



i-tc., r 

 jjrown 



etc.. twent 

 trt-c. A\ kini 

 is the "dca 



years of the life of tin- 

 s; the shaded part of each 

 knot " of lumber. 



